Gerhard Gentzen was a German mathematician and logician, born on July 24, 1909, and known for his significant contributions to the foundations of mathematics. He is best recognized for developing natural deduction and sequent calculus, two important systems in formal logic that help in understanding mathematical proofs and reasoning. Gentzen's work laid the groundwork for many areas in mathematical logic and proof theory. His ideas influenced later developments in proof theory and type theory, and he is often regarded as one of the key figures in 20th-century logic. Gentzen's research continues to be relevant in various fields, including computer science and philosophy.